This invention relates to electrical appliances. The invention relates more particularly to improvements in electrical appliances of the type adapted to provide a stream of heated air.
In one form of electrical appliance, an electrical heater is mounted in a housing and an air stream, which is established in the housing, flows about the heater. The air stream which is thus heated is discharged from an outlet aperture of the housing and is utilized for hair treatment by curling, styling or drying.
In a particular form of this type of appliance, the heater includes an electrical resistance element which is wound in a generally helical configuration about an electrically resistive and thermally insulating support means of cruciform cross section. A heater element support means formed of mica has been utilized and is particularly useful since it exhibits desired electrically and thermally insulating characteristics.
Appliances utilizing heater arrangements of this tye have exhibited several disadvantageous characteristics. Air which is caused to flow in a stream about the heater has a cyclonic or swirling flow pattern and flows adjacent to inner surfaces of the housing thereby resulting in insufficient contact with segments of the heater element. Prior arrangements have reduced this swirling pattern to some extent by providing air vanes which cause the flow pattern to assume a more longitudinal direction. The air vanes however have been aligned with support members of the heater support means and while reducing the swirling characteristics, nonetheless result in excessive heating and glowing of heater element segments at transverse locations between the support members. These excessively hot heater element segments cause undesirable hot spots on the housing which are evident to the touch.
In a known heater arrangement, a heater element support means of cruciform cross section and which is formed of mica has been provided through the use of a pair of mica plates. These plates are slotted and are adapted for mutual engagement. The assembled plates have proven to be relatively non-rigid and reinforcement means are generally required in order to establish a relatively rigid assembly. The reinforcement means which comprises braces, for example, increases the cost of the heater element support means both in terms of additionally required parts and additional time and labor required in the assembly.
While it is desirable to provide a heater element which is continuously wound in a generally helical configuration on the support means, it is also desirable to provide means for tapping the heater element at locations which are electrically intermediate ends of the heater element. In prior arrangements, this has been accomplished by interrupting mechanical continuity in the winding in order to establish the desired tap. This interruption in the helical winding undesirably requires additional time in the assembly of the heater which increases the cost of the heater.
The use of mica as a heater support means is preferable because of its desirable electrically and thermally insulative physical characteristics. However, this material and other suitable equivalent materials exhibit a brittleness which frequently results in breakage of the mica at locations in the appliance where the mica is supported.
Accordingly, it is an object of this invention to provide an improved electrical appliance having means for heating an air stream.
Another object of the invention is to provide an electrical appliance having a resistive heater element about which an air stream flows and wherein relatively enhanced uniform heating of the air stream is provided.
Another object of the invention is to provide an improved heater arrangement in an electrical appliance which eliminates excessively hot segments along the heater element.
Another object of the invention is to provide an improved heater of substantially rigid construction.
A further object of the invention is to provide an improved means for tapping a heater element in an electrical appliance.
Another object of the invention is to provide an improved means for supporting a resistance heater formed of a relatively brittle support material and for effecting electrical contact with the heater element.